The present invention concerns a transmission for a wind-power plant.
Contemporary wind-power plants are increasingly affected by ecological and environmental demands. Economy requires that up-to-date plants compete with such conventional methods of harvesting energy as fossil-fueled and nuclear-power plants. This demand assumes the availability of high-output, light weight-per-output, and compact systems. Strength and environmental considerations (e.g. noise) on the other hand require the reduction of dynamic stress. The sites must be as continuous in area, as exposed to strong winds, and as low-populated as possible. One possibility is offshore plants, which, due to the additional expenditure involved in installation, must be even more powerful and compact and lighter in weight.
The transmission trains employed in known wind-power plants (European Published Patent 635 639) comprise rotor blades, a hub with a shaft and bearing set, a multiple-stage planetary gear, a coupling, and a generator. The blades are mounted on the hub and rotate the shaft. The shaft is accommodated in a large roller bearing connected to an azimuth bearing by way of a frame. The force of the wind against the rotor are accordingly transmitted to a mast. This bearing system requires interposing part of the shaft between the rotor and the transmission. The downstream roller bearing consists of a transmission section with a hollow input shaft that is connected to the rotor shaft by an overturned disk. The overall transmission is also mounted on the frame by way of a two-armed torque-accommodating strut, This known wind-power plant occupies a lot of space and is accordingly restricted in output.
European Published Patent 811 764 describes a wind-power plant wherein the rotor is integrated directly into the base of a single-stage planetary transmission. The transmission and its generator are mounted on the same frame.
WIPO 96/11338 describes a two-stage planetary transmission with two simple-cogged planetary wheels and intended for a wind-power plant. The rotor is directly integrated into the planetary base and its bearing set is accommodated in a housing. How the transmission is connected to the plant itself is not described.
The object of the present invention is a wind-power plant that is more compact and accordingly appropriate for higher outputs, of 2.5-5 MW, is only slightly heavier, and is less complicated.
Directly connecting the hub to the input stage of the two-stage planetary transmission renders the transmission more compact. The device can be even more compact if the hub is connected to the transmission""s housing, in which event the whole transmission can be housed in the hub. The double-helical cogs in the input stage and the single-helical cogs on the planetary wheels in the output stage ensure higher transmission ratios in less space. Furthermore, the transmission in accordance with the present invention needs no frame, and its or the generator""s housing can be directly connected to the azimuth bearing.